Molecular sieves are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, framework-type zeolites and other crystalline microporous molecular sieves, for which a structure has been established, are assigned a three letter code and are described in the Atlas of Zeolite Framework Types, 6th edition, Elsevier, London, England (2007). MCM-68 is one of the molecular sieves for which a structure has been established and materials of this framework type are designated as MSE.
MSE framework-type molecular sieves have a 3-dimensional channel structure comprising one 12-membered ring channel system and two 10-membered ring channel systems, in which the channels of each system extend perpendicular to the channels of the other systems and in which the 12-ring channels are generally straight and the 10-ring channels are tortuous (sinusoidal).
The composition and characterizing X-ray diffraction pattern of MCM-68 are disclosed in U.S. Pat. No. 6,049,018, which also describes the synthesis of the molecular sieve in the presence of a structure directing agent comprising N,N,N′,N′-tetraethylbicyclo-[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dications and/or N,N,N′,N′-tetraalkylbicyclo-[2.2.2]octane-2,3:5,6-dipyrrolidinium dications. The entire contents of U.S. Pat. No. 6,049,018 are incorporated herein by reference.
U.S. Pat. No. 8,025,863 discloses that MSE framework-type molecular sieves can be synthesized using a structure directing agent selected from 1,1-dialkyl-4-cyclohexyl-piperazin-1-ium cations, 1,1-dialkyl-4-alkylcyclohexylpiperazin-1-ium cations and mixtures thereof. The entire contents of U.S. Pat. No. 8,025,863 are incorporated herein by reference.
U.S. Patent Application Publication No. 2013/0095030 discloses that MSE framework-type molecular sieves can be synthesized using a structure directing agent having one or both of the two following general structures:
where A is a >CR13R14 group, a >C═O group, or an >O group, where R1, R2, R3, R4, R7, R8, R9, and R10 are each independently hydrogen, a hydroxyl group, or a C1-C5 hydrocarbon chain, where R13 and R14 are each independently hydrogen or a C1-C5 hydrocarbon chain, where R5, R6, R11, and R12 are each independently a C1-C5 hydrocarbon chain, and where one of the R5 and R6 groups can alternately be connected to one of the R13 and R14 groups to form a C1-C5 hydrocarbon linking moiety. The entire contents of U.S. Patent Application Publication No. 2013/0095030 are incorporated herein by reference.
U.S. Patent Application Publication No. 2013/0115163, the entire contents of which are hereby incorporated by reference herein, discloses that MSE framework-type molecular sieves can be synthesized using a structure directing agent comprising one or more of the following dications: 3-hydroxy-1-(4-(1-methylpiperidin-1-ium-1 yl)butyl)quinuclidin-1-ium, 3-hydroxy-1-(5-(1-methylpiperidin-1-ium-1-yl)pentyl) quinuclidin-1-ium, 1,1′-(butane-1,4-diyl)bis(1-methylpiperidin-1-ium), 1,1′-(pentane-1,5-diyl)bis(1-methylpiperidin-1-ium), 1,1′-(hexane-1,6-diyl)bis(1-methylpiperidin-1-ium), and 1,1′-((3as,6as)-octahydro-pentalene-2,5-diyl)bis(1-methylpiperidin-1-ium).
MSE framework-type molecular sieves have attracted interest as catalysts for fluid catalytic cracking (FCC) of hydrocarbon feeds since they generate high yields of propylene. However, this interest has been limited by the tendency for MSE framework-type to undergo rapid aging, particularly during catalyst regeneration. There is therefore interest in producing MSE framework-type molecular sieves with improved lifetime, especially in FCC catalytic applications.